The invention relates to a container of the type described in the preamble of the main claim. Such container is known from EP-0 349 053.
This known container comprises a pressure capsule having a first, second and third chamber, the first chamber being filled with a pressurised gas to be discharged into the inner space of said container. On top of said first chamber the second and third chamber are positioned, said third chamber being positioned between the first and second chamber. An outlet opening is provided between said first and third chamber, provided with a closing member biased in a closed position by a spring. The second chamber is separated from the third chamber by a membrane. During operation an operating pressure prevails in the second chamber, moving said membrane depending on the pressure in the third chamber, which during use can freely communicate with the inner space of the container. When the pressure drops in the third chamber, the membrane is moved against the closing member, thereby forcing the closing member to an opening position, such that pressurised gas can be discharged from the first chamber through the third chamber into the inner space. Consequently, the pressure rises in the third chamber, thereby forcing the membrane into the direction of the second chamber, once again closing the closing member.
In this known container, before use, a meltable means is provided for keeping the closing member from being operated by said membrane. In a first embodiment this is achieved by providing said meltable member in the opening between the third chamber and the environment, after pressurising the third chamber to a pressure above the operating pressure prevailing in the second chamber during use. In a second embodiment a ring-shaped meltable element is provided around part of the closing member, thereby preventing movement of said closing member before melting said meltable member.
This known container has the disadvantage that said container has to be heated prior to use, for melting said meltabel member, thereby contaminating the fluid to be dispensed and heating said fluid, which may be undesirable. Furthermore, such container is difficult to assemble and cannot be stored easily over relatively long periods.
A further container having pressurising means is known from FR-A-2 690 142.
This known container comprises an inner space in which a fluid to be dispensed is included, which inner space accommodates a pressure vessel with pressure control means. In the pressure vessel, a first chamber is formed into which a gas is introduced under relatively high pressure, while an outlet opening is provided which is closed by a closing member. This closing member is slightly rod-shaped and is surrounded in the outlet opening by an O-ring which tightly seals thereagainst. Provided in the rod-shaped element is a circumferential groove. In the pressure vessel, a second chamber is formed opposite the first chamber, which second chamber, on she side proximal to the first chamber, is closed by a membrane to which the rod-shaped element is attached by one end thereof. In the second chamber, a control pressure is created by means of a gas. Included between the first and the second chamber is a third chamber through which the rod-shaped element extends and which is provided with an opening forming a fluid connection between the third chamber and the inner space of the container.
When in this known apparatus a desired pressure prevails in the third chamber, for instance a pressure equal to the control pressure, the groove is located in the third chamber and the outlet opening is closed by the rod-shaped element. When fluid is dispensed from the inner space, the pressure therein will fall, resulting in the same pressure fall in the third chamber. Consequently, the membrane-shaped wall part of the second chamber will deform in the direction of the first chamber, while moving the rod-shaped element axially, further into the first chamber. When the groove has been moved to the level of the O-ring, gas under pressure will be able to escape via the groove and along the O-ring from the first chamber to the third chamber, and from there to the inner space of the container. This causes the pressure in the third chamber to rise such that the membrane-shaped wall part is deformed back, against the control pressure, while it moves the rod-shaped element along from the first chamber. When the rod-shaped element is again sealingly clasped by the O-ring, no gas will be able to escape from the first chamber anymore, in which condition the pressure in the third chamber and the inner space is again approximately equal to the desired pressure, in this case the control pressure.
This known container has the drawback that already before the gas is introduced under pressure into the first chamber, the closing member and the control means therefor, in this case the second chamber, the membrane-shaped wall part and the rod-shaped element, must have been fitted. The first chamber is filled by pressing gas under particularly high pressure into the third chamber via the opening, such that the membrane-shaped element is deformed in the direction away from the first chamber. This involves the rod-shaped element being pulled from the first chamber so far that a slightly tapering end thereof is located in the outlet opening. The gas can then pass this end under high pressure and be introduced into the first chamber. Upon removal of the high gas pressure, the rod-shaped element will be moved into the outlet opening again under the influence of the control pressure and close said outlet opening. This has the drawback that the introduction of the gas under pressure is relatively complicated and should be effected through relatively small openings. Moreover, there is the danger that in the case of unduly high filling pressure, the rod-shaped element is pulled from the first chamber entirely and will not return into the outlet opening when the gas pressure is removed, for instance in that the rod-shaped element swivels slightly while the closing O-ring can be pressed from the opening. Moreover, during filling, relatively large deformations of the membrane-shaped wall part will occur. When, after the gas has been introduced into the first chamber, this known apparatus is stored for some time, the control pressure will act on the membrane-shaped element continuously without a desired counterpressure prevailing in the third chamber. After all, the pressure in the third chamber will then be substantially atmospheric. As a consequence, the membrane will be held in a relatively highly deformed state for a relatively long time, which is disadvantageous to the elastic properties thereof. Moreover, this entails the risk of a change of the control pressure caused by gas leaking away from the second chamber along or through the highly deformed membrane.
Moreover, in the case of leakage of the membrane, the control pressure may fall out, so that the closure will be lost and the gas from the first chamber will flow freely to the container, as a result of which the container will be subjected to an unduly high pressure.
A further drawback of this known apparatus is that the rod-shaped body closes the outlet opening of the second chamber by means of an O-ring. This O-ring will continuously be subjected to the high gas pressure in the second chamber. This means that when the O-ring and/or the rod-shaped element are not positioned and/or dimensioned exactly properly, gas can simply flow away between the rod-shaped element and the O-ring. This, too, will eventually cause the gas to flow away from the first chamber to the container and build up an unduly high pressure therein. This is undesirable, both because of the unduly high pressure build-up and because of the poor functioning of the fluid dispensing operation.
The object of the invention is to provide a container of the type described in the preamble, in which the drawbacks of the known container are avoided while the advantages thereof are maintained. In particular, the object of the invention is to provide a container with a pressure control device for maintaining a substantially constant, preset pressure in the container, with the pressure control device enabling simple filling with a pressure fluid and maintaining its pressure-controlling action during relatively long times. To that end, a container according to the present invention is characterized by the features of claim 1.
In a container according to the present invention, pressure fluid can be received and retained in the first chamber without the control means and/or the second chamber having been fitted. Indeed, the closing member is biased in the closed position and will keep the passage opening closed at all times when the control member, at least the second chamber, has been removed, or at least the pressure-controlling action thereof has been put out of operation. The advantage thus achieved is that the control means can be fitted after the first chamber has been filled, while the control means can moreover be stored and transported separately from the first chamber. In addition, there is achieved the advantage that, starting from the same first chamber, different control means can be applied, depending on, for instance, the desired control pressure, a desired travel of the operating member and the like. This also prevents the closing member from being operated prematurely. Indeed, the closing member can be operated by the control means only after assembly. Preferably, the first chamber is filled along the closing member with gas or another pressure fluid under high pressure, but the first chamber can also be filled prior to the positioning of the closing member.
In an advantageous elaboration, an apparatus according to the present invention is characterized by the features of claim 2.
Positioning the closing member at least substantially on the side of the passage opening facing the first chamber offers the advantage that during use, the closing member will be forced in the direction of the passage opening and against the seating under the influence of the pressure prevailing in the first chamber, so as to close the passage opening. Through the provision of limit means which limit the maximum travel of the closing member, the closing member is readily prevented from entering the first chamber loosely. By designing the limit means in a suitable manner, it is provided that pressure gas can be introduced into the first chamber via the passage opening, while passing the closing member in a simple manner. To that end, the limit means may, for instance, be provided with ribs, slots or passage openings, such that the closing member in a position in which it has moved away from the passage opening can abut against at least a part of said ribs or material present between said slots or openings, while releasing fluid connections between the passage opening and the closing member on the one hand and recesses located between said ribs or the slots or passage openings on the other. Also, such ribs, slots or openings may be incorporated into a side, facing away from the seating, of the closing member itself.
It is preferred that as biasing means, spring means be used which bias the closing member in the closed position, also when no excess pressure is present in the first chamber. This readily prevents contamination of the inner space of the first chamber, while, moreover, no gases or solid substances can escape therefrom.
In a further advantageous embodiment, a container according to the present invention is characterized by the features of claim 3.
In such container, the advantage is achieved that the principal direction of movement of the control means will not coincide with the principal direction of movement of the closing member, which creates a greater freedom of design and moreover allows greater tolerances. Indeed, in the case of coinciding principal directions of movement, the position of the second chamber, at least of the control means, will have to be determined particularly accurately with respect to the closing member in at least the closed position. A further advantage of such container may be that an unintentional movement of the control means in the principal direction of movement of the closing member will not, or at least not directly, result in a movement of the closing member. Thus, unintentional release of gas is prevented yet more effectively.
The control means preferably extends at least substantially entirely outside the first chamber, enabling it to be removed in a simple fashion. After all, this does not involve the release of an opening in the first chamber.
In a particularly advantageous embodiment, a container according to the present invention is further characterized by the features of claim 5.
The use of at least a part of a valve as closing member offers the advantage that a closing member biased in the closed position can easily be obtained. The advantage achieved by arranging this in such a manner that it can be opened by at least the control means, is that by means of such valve, a self-regulating pressure control device can be obtained in a container according to the present invention.
In a further advantageous embodiment, a container according to the present invention is characterized by the features of claim 7.
Detachably connecting the control means to the closing member enables positioning the closing member relative to the control means in a relatively simple manner, while movement of the closing member by the control means can readily be effected. A snap connection enables such coupling in a relatively simple manner. Moreover, this may simply prevent detachment of the control means from the closing member, thus preventing malversation.
In a preferred embodiment, a container according to the present invention is characterized by the features of claim 9.
By accommodating the first chamber in a first housing and accommodating the second chamber in a second housing, which housings can be coupled via coupling means, a container according to the present invention can be obtained in a constructionally simple manner. In particular the use of a snap connection enables such coupling in a highly simple manner. Such snap connection is preferably of such design that it cannot be detached again without any problem. As a matter of fact, it will be appreciated that other coupling means can be used as well, for instance bayonet coupling means, screw thread connections or the like.
In an alternative embodiment, there is provided a filling opening for the first chamber, located at a distance from the passage opening. The advantage thus achieved is that the first chamber need not be filled through the passage opening.
In a further alternative embodiment, a container according to the invention is characterized by the features of claim 11.
By collecting gas egressing from the first chamber in a balloon-shaped or otherwise expandable element, the advantage achieved is that contact between and mixing of the fluid to be dispensed and the pressure fluid is prevented. This is in particular advantageous when, for instance for toxic or chemical reasons, the pressure fluid must not be dispensed, or at least not together with the fluid to be dispensed.
The invention further relates to a pressure control device for use in a container according to the invention.
Such pressure control device according to the invention is preferably characterized by the features of claim 13.
By using an intermediate part which can be coupled to the first chamber and which comprises at least the passage opening and the closing member, a relatively simple housing for the first chamber can be obtained with a suitable passage opening. At the desired moment, the second chamber with the control member can then be placed and coupled to the intermediate part, such that the desired pressure control device is obtained, or at least brought into a condition in which it is ready for use. According to the use, a suitable second chamber with suitable control member can in each case be selected.
The invention further relates to a method for preparing a container for dispensing a fluid under substantially constant pressure, characterized by the features of claim 14.
With such method, there is readily obtained a container which, to a user, is directly ready for use. When a part of the fluid contained in the container is removed therefrom, the pressure in the container will in principle decrease. By means of the pressure control device, an amount of pressure fluid, in particular a gas, will thereupon be released from the first chamber to compensate for said pressure decrease. Preferably, the pressure in the inner space of the container is controlled such that it is sufficient for pressing the fluid from the container at a desired pressure. However, it will be understood that it is also possible to control the pressure in the inner space at a relatively low level, for instance atmospheric or subatmospheric, while the fluid introduced into the inner space can, for instance, serve as shielding gas or be used to prevent the occurrence of a reduced pressure in the inner space, which, after all, will prevent the fluid from being dispensed or will at least render it more difficult.
The invention moreover relates to the use of a container or a pressure control device according to the invention for dispensing carbonated beverage, in particular beer, under substantially constant pressure, and to the use of a method according to the present invention therefor.
As pressure fluid, preferably a gas, in particular CO2 or CO2-containing gas, is used in an apparatus or method according to the invention. However, another pressure medium may be used as well, for instance a liquid. Also, a pressure fluid may be obtained in a chemical manner, for instance by combining calcium, (bi) carbonate and an acid such as citric acid. Thus, a pressure gas, in particular CO2, is created. Many variations thereof are possible. The (bi) carbonate or another, calcareous product may be included in the third chamber, at least on the opposite side of the closing member.